This invention relates to an electronic ignition signal distributor for automobile engine and, particularly, to a fail-safe electronic circuit arrangement for the ignition signal distribution system.
The conventional electronic ignition signal distributor operates to distribute the ignition signals to the ignition devices of the engine by determining the ignition sequence of the cylinders using a counter circuit in response to the detection of the timing for the reference cylinder. However, if the counter operates false due to a noise or the like, an irrelevant cylinder can be ignited erroneously, and such an event can damage the engine.
There has been proposed an ignition signal distribution system having a constitution for preventing the false operation of an electric distributor, due to double count by a counter because of a stop operation of the engine with a reversal rotation, as disclosed in Japanese Patent Publication No. 59-28751. This electronic ignition signal distributor, however, does not protect the ignition signal distribution properly in the event of a false operation, due to a noise or the like, of the counter for determining the cylinder to be ignited, resulting possibly in the ignition of an irrevelant cylinder which is in the suction stroke, for example.